Can the Law of the Colorado River Adapt to an Increasingly Drier Hydrology?

A Two-Part Article by John McClow, UGRWCD Legal Counsel

PART 2 – Colorado River Compact

Adapting the Law of the River for a Dry Hydrology

Lake Powell storage levels began declining in 2000, and by the end of 2004 were at an alarmingly low elevation. As a result, the Upper Basin States requested that the Secretary of the Interior reduce releases from Lake Powell. Instead, she ordered the seven Colorado River Basin States to work with the Bureau of Reclamation to agree to address reservoir operations in dry hydrology. The parties complied, and the result is the Interim Shortage Guidelines, embodied in a Record of Decision signed by the Secretary of the Interior in 2007, which will remain in effect through December 31, 2025 (2007 Guidelines). The 2007 Guidelines provide for coordinated operation of Lake Powell and Lake Mead during the Interim Period, the objectives of which are to avoid curtailment of uses in the Upper Basin, minimize shortages in the Lower Basin and not adversely affect the yield for development available in the Upper Basin. Annual releases from Lake Powell are determined according to storage levels in Powell and Mead so that equalization of storage in the two reservoirs can be achieved as nearly as practicable each year. The Guidelines establish the conditions under which the Secretary of the Interior will declare a shortage in the Lower Basin and apportions the shortage between Arizona and Nevada. The 2007 Guidelines were the beginning of a new era of collaboration among the seven Colorado River Basin States and Reclamation to address the need to adapt the Law of the River to historically dry conditions.

The 2007 Guidelines were moderately successful in meeting their objectives. Still, by Summer 2013, the extent of the 2012-2013 drought created concerns among Colorado River Basin water managers, including the Secretary of the Interior. All of the models reached similar conclusions:  without adjustment to reservoir operations, there was a 20% probability that reservoir levels could reach critical levels within two years if current conditions continued. The seven states convened meetings of legal and technical working groups to develop a contingency plan to respond quickly to the models’ worst-case scenarios. The groups met with the states’ principals in early 2014 and presented a spreadsheet of possible actions for immediate drought response. It became clear that the solutions for the Upper and Lower Basins were sufficiently different that the groups should split and work on their plans separately, but with coordination between the Upper and Lower Basin teams. The result was a Drought Contingency Plan (DCP) for each Basin.

The Lower Basin DCP directs that as Lake Mead reaches lowering storage levels, the states must reduce their consumptive use of Colorado River water (called “taking shortages”) based on storage tiers contained in the 2007 Guidelines and supplemented by the DCP. The DCP also provides that California will also take shortages if Lake Mead declines to critical storage levels. Lake Mead storage has fallen to the point that in 2022 the DCP requires Arizona to take a shortage of 512,000 acre-feet and Nevada 21,000 acre-feet. The Lower Basin states announced the “500 Plus Plan” in December 2021. They pledged to collectively preserve 500 acre-feet of storage in Lake Mead in 2022 and 2023 – evidence of additional adaptation in response to the dry hydrology.

The Upper Basin DCP consists of three elements: (1) expand existing weather modification (cloud seeding) and phreatophyte removal; (2) extended operations of the upper CRSP reservoirs (Blue Mesa, Flaming Gorge, Navajo); and (3) development of a demand management program. Although its contribution is relatively small, the states have aggressively pursued the first element. To implement the second element, the Upper Basin States entered into a Drought Response Operations Agreement (DROA), which provides for additional releases from the upper CRSP reservoirs to maintain critical storage levels at Lake Powell. In July, the Secretary of the Interior exercised her emergency authority under the DROA to release 181,000 acre-feet from Flaming Gorge, Blue Mesa, and Navajo Reservoirs. The states and Reclamation are developing additional criteria for future releases under the DROA. Reclamation does not presently contemplate further releases in 2022. The Upper Basin States are heavily involved in evaluating the advisability and feasibility of the third element, a demand management program that contemplates voluntary, temporary, compensated reductions in consumptive use by Upper Basin water users of all types for compliance with the 1922 Compact.

In addition to the Drought Contingency Plans, the United States has negotiated supplements to the 1944 Treaty. Mexico has agreed to share shortages by taking reductions in its deliveries in amounts comparable to the shortages taken by the Lower Basin States under their DCP.

What Does the Future Hold?

Despite these significant collaborative efforts by the Colorado River Basin States and the Bureau of Reclamation to adapt the Law of the River to changing conditions, reservoir levels have continued to decline, so a significant challenge remains. As the states and Reclamation begin renegotiating the 2007 Guidelines – to further adapt to drier hydrology – all parties have pledged to continue collaborating on mutually beneficial solutions to address that remaining challenge. History indicates that they will succeed.